This invention relates generally to farm vehicles such as combines or the like and, more particularly, to an improved rock trap for a farm vehicle for preventing rocks from entering the threshing area of the combine.
It is known that in the use of farm vehicles such as combines for harvesting crops, the crop material is picked up from the ground or cut direct from the ground by a header and fed by a conveyor system through a feeder house or chute to the threshing portion of the machine. This is true both in conventional drum or cylinder type threshing machines and in rotary threshing machines.
Prior to the present invention, a rock ejector apparatus was provided for certain types of combines. The rock ejector extended across the feeder house, intermediate the headers and the threshing area, and rocks coming into contact with the rock ejector were ostensibly pushed downward through a closeable doorway in the bottom of the feeder house. Such rock ejectors have been singularly unsuccessful in preventing rocks from entering the threshing area.
The damage caused to threshing machines by rocks is extremely serious in several respects. First of all, a rock entering the threshing area can damage the threshing drum or rotors, depending upon whether a standard or rotary combine is being used, thus damaging the threshing machine and rendering the same inoperable until repaired. Rocks of sufficient size which enter the threshing area are oft times moved with such force that they break through the metal walls of the combine resulting in even further damage. The damage cannot be measured solely in terms of the expense of repairing the combine but must also be measured in terms of the loss of productivity of the machine in harvesting crops, especially since the harvesting season is of short duration. The failure to harvest crops at the appropriate time can render the crops worthless and the financial loss thus incurred is far greater than the cost of repairing the combine.
The problem of rocks entering the feeder house and ultimately reaching the threshing area are so severe and the ineffectiveness of a rock ejector is so well understood that the manufacturers of combines will not provide any warranty or guarantee against the type of rock damage when selling combines.
Accordingly, prior to the present invention, there was no effective technique for removing rocks from crop material being harvested and thus preventing not only the costly repairs to the combine but also the potential loss of crops due to the inability to use a machine while it is being repaired.